Introduction to Stored Procedures
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What is a primary purpose of a stored procedure?

  • To perform specific functions using multiple commands (correct)
  • To execute only a single query at a time
  • To generate user interface elements
  • To store data permanently

    • What types of parameter modes are recognized in a stored procedure?

  • IN, OUT, MULTI
  • IN, OUT, INOUT (correct)
  • IN, PARAM, OUT
  • IN, OUT, BOTH

    • Which keyword is optional when defining a stored procedure?

  • Create Procedure
  • Begin
  • Replace (correct)
  • End

    • Which statement is true regarding the datatype of parameters in a stored procedure?

    <p>The datatype does not take a specific length</p> Signup and view all the answers

    Where do parameters appear in the definition of a stored procedure?

    <p>After the procedure name</p> Signup and view all the answers

    What is the effect of using the 'IS' or 'AS' keywords in a stored procedure?

    <p>To declare and define internal variables</p> Signup and view all the answers

    Which of the following statements correctly describes the 'IN' parameter type?

    <p>Passes a fixed value from the calling environment to the procedure</p> Signup and view all the answers

    Can a stored procedure call another stored procedure?

    <p>Yes, it can be called inside another stored procedure</p> Signup and view all the answers

    What is a key characteristic that differentiates stored functions from stored procedures?

    <p>Stored functions must contain a return statement.</p> Signup and view all the answers

    Which statement is true regarding the parameters of stored functions?

    <p>Stored functions can have zero or more parameters.</p> Signup and view all the answers

    What is contained within the body of a stored function?

    <p>Code structured between the keywords IS and END.</p> Signup and view all the answers

    Which of the following statements about stored procedures is correct?

    <p>Stored procedures can modify table data.</p> Signup and view all the answers

    What happens when a stored function is deleted?

    <p>All associated data is lost permanently.</p> Signup and view all the answers

    What must be specified in the header of a stored function?

    <p>The parameters and the return value's data type.</p> Signup and view all the answers

    Which operation is not allowed in a stored function?

    <p>Executing an INSERT statement.</p> Signup and view all the answers

    In what scenario are stored functions called?

    <p>As part of an expression.</p> Signup and view all the answers

    What happens if a transaction fails after some operations have been executed?

    <p>The system reverts to its state before the transaction began.</p> Signup and view all the answers

    What is a key benefit of using functions and procedures in programming?

    <p>They improve program maintenance and monitoring.</p> Signup and view all the answers

    Which command is used to permanently save changes in a transaction?

    <p>Commit</p> Signup and view all the answers

    What defines a transaction in the context of database operations?

    <p>A set of sequential operations that must all succeed or all fail.</p> Signup and view all the answers

    What is a rollback in the context of transactions?

    <p>The action of undoing changes made by a transaction that failed.</p> Signup and view all the answers

    When does a transaction end?

    <p>When the commit command is executed or the program is closed.</p> Signup and view all the answers

    Which of the following is NOT a movement that can be classified as a transaction?

    <p>Applying for a bank loan.</p> Signup and view all the answers

    Which scenario best describes a database transaction?

    <p>Ordering an item online and paying for it.</p> Signup and view all the answers

    What is the primary purpose of data bindings in forms?

    <p>To connect form elements to model attributes</p> Signup and view all the answers

    Which step is NOT involved in building models to display data from tables?

    <p>Implement user access controls</p> Signup and view all the answers

    What is a key benefit of formatting forms?

    <p>Enhanced user experience</p> Signup and view all the answers

    What type of model should be chosen based on specific requirements for data display?

    <p>Bound or unbound model</p> Signup and view all the answers

    What is the primary function of command buttons in forms?

    <p>To trigger actions or navigation</p> Signup and view all the answers

    Which architectural model do Oracle Forms applications typically utilize?

    <p>Client-server architecture</p> Signup and view all the answers

    What role do drop-down lists serve in forms?

    <p>To provide users with predefined options</p> Signup and view all the answers

    What must be implemented to ensure that data adheres to table constraints?

    <p>Data validation</p> Signup and view all the answers

    What does an AFTER trigger do?

    <p>It gets executed after a specific event has taken place.</p> Signup and view all the answers

    Which prefix can be used to see the old value of a column in a trigger?

    <p>:old</p> Signup and view all the answers

    In which scenario is the INSTEAD OF trigger specifically used?

    <p>When working with a view to modify DML actions.</p> Signup and view all the answers

    What kind of trigger is executed for events like SHUTDOWN or LOGON?

    <p>Database trigger</p> Signup and view all the answers

    What is the purpose of the FOR EACH ROW clause in a trigger?

    <p>To ensure the trigger fires for each row affected by a DML operation.</p> Signup and view all the answers

    Which of the following statements is correct about a DDL trigger?

    <p>It gets executed during structural changes, such as ALTER.</p> Signup and view all the answers

    What does the CREATE OR REPLACE statement do in the context of triggers?

    <p>Creates a new trigger or replaces an existing trigger with the same name.</p> Signup and view all the answers

    Which SQL command is applicable to specifying the condition for row-level triggers?

    <p>WHEN condition</p> Signup and view all the answers

    Study Notes

    Stored Procedures

    • A stored procedure is a named, pre-compiled unit of code stored in a database.
    • It performs a specific task and can be called multiple times.
    • Similar to anonymous software modules but uses "IS" or "AS" instead of "Declare".
    • Can be executed and called multiple times because it's stored in the database.
    • Can contain parameters, which means they can use input and output values.
    • Stored procedures can be called inside other stored procedures.

    Stored Procedure Syntax

    • CREATE PROCEDURE [OR REPLACE] procedure_name (Parameter)
      • CREATE PROCEDURE: Keyword for creating a stored procedure.
      • OR REPLACE: Optional keyword for replacing existing procedures with new versions.
      • procedure_name: Name of the procedure.
      • Parameter: List of parameters with their mode, datatype, and name.

    Parameters

    • Operands used to pass values to and from the database.
    • Three modes:
      • IN: Passes a fixed value from the calling environment to the procedure.
      • OUT: Passes a value from the procedure to the calling environment.
      • IN OUT: Passes a value from the calling environment to the procedure and returns a value back using the same parameter.

    Stored Functions

    • Created and defined by the user and have similar properties to stored procedures.
    • The difference is that stored functions return a value using the RETURN command.
    • Stored functions can have zero or more parameters but must have one return value.

    Stored Function Syntax

    • CREATE OR REPLACE FUNCTION function_name (parameter) RETURN datatype AS
    • function_name: Name of the function.
    • parameter: List of parameters with their mode, datatype, and name.
    • RETURN datatype: Specifies the data type of the value that the function returns.

    Comparing Stored Procedures and Functions

    Feature Stored Procedure Stored Function
    Execution Inside a PL/SQL statement As part of an expression
    Return Value Can have one or two return values using OUT parameter Must contain a RETURN statement with a single return value
    Data Modification Can modify data in tables using DML statements Cannot modify data in tables; can only execute select statements

    Benefits of Stored Procedures and Functions

    • Improved efficiency
    • Enhanced maintainability and monitoring of code.
    • Improved data protection opportunities.

    Transactions

    • A transaction is a logical unit of work consisting of several operations that either succeed together or fail together.
    • Ensures data consistency and integrity.
    • Examples: Bank withdrawals, online purchases, flight ticket reservations.
    • A transaction is considered successful if all operations within it succeed.
    • If any operation fails, the entire transaction fails, and the system is rolled back to its previous state.

    Transaction Commands

    • BEGIN TRANSACTION: Starts a transaction.
    • COMMIT: Saves changes made to the database.
    • ROLLBACK: Undoes all changes within the transaction.

    Triggers

    • Automated code blocks that execute in response to specific events.
    • Can be triggered for various events:
      • DML: Data Manipulation Language events (INSERT, UPDATE, DELETE).
      • DDL: Data Definition Language events (CREATE, ALTER, DROP).
      • DATABASE: Database events (SHUTDOWN, STARTUP, LOGOFF, LOGON).

    Trigger Syntax

    • CREATE OR REPLACE TRIGGER trigger_name BEFORE/AFTER/INSTEAD OF INSERT/UPDATE/DELETE ON table_name [FOR EACH ROW] WHEN (condition) {BEGIN ... END;}
    • trigger_name: Name of the trigger.
    • BEFORE/AFTER/INSTEAD OF: Specifies when the trigger should fire.
    • INSERT/UPDATE/DELETE: Indicates the DML event that triggers the trigger.
    • ON table_name: Identifies the table associated with the trigger.
    • FOR EACH ROW: Specifies a row-level trigger; if omitted, it's a table-level trigger.
    • WHEN (condition): An optional condition specifying when the trigger should execute for row-level triggers.
    • BEGIN ... END: Encloses the trigger code.

    Trigger Conditions

    • :OLD: Represents the previous value of a column before the DML operation.
    • :NEW: Represents the new value of a column after the DML operation.

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    Description

    This quiz explores the fundamental concepts of stored procedures, including their syntax, functionality, and parameters. Understand how stored procedures are created, executed, and how they facilitate database interactions. Test your knowledge of this essential aspect of database management.

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